Electronic apparatus capable of determining whether to execute power supply to control portion at start of power supply from outside

Abstract

An electronic apparatus includes a control portion, a signal output circuit, a switching processing portion, and a determination processing portion. The control portion switches on or off power supply from the primary power source in response to detection of an operation on a power switch. The signal output circuit outputs a preset digital signal. The switching processing portion switches a signal level of the digital signal when a power supply state of the control portion is switched. The determination processing portion determines whether or not to execute power supply to the control portion based on the signal level of the digital signal output by the signal output circuit when power supply from an external power source to the primary power source is started.

The invention claimed is: 
     
         1 . An electronic apparatus comprising:
 a primary power source configured to receive power supply from an external power source;   a control portion configured to switch on or off power supply from the primary power source in response to detection of an operation on a predetermined power switch;   a signal output circuit configured to receive power supply from the primary power source and output a preset digital signal during power supply from the external power source to the primary power source, and receive power supply from a predetermined secondary power source and output the digital signal during power supply stop from the external power source to the primary power source;   a switching processing portion configured to switch a signal level of the digital signal when a power supply state of the control portion is switched; and   a determination processing portion configured to determine whether or not to execute power supply to the control portion based on the signal level of the digital signal output by the signal output circuit when power supply from the external power source to the primary power source is started.   
     
     
         2 . The electronic apparatus according to  claim 1 , wherein
 in the signal output circuit, no current flows during output of the digital signal at a first level, and a current flows during output of the digital signal at a second level,   the switching processing portion switches the signal level of the digital signal from the first level to the second level when the power supply to the control portion is started.   
     
     
         3 . The electronic apparatus according to  claim 1 , further comprising one or both of an image reading portion configured to read an image of a document sheet and an image forming portion configured to form an image based on image data.